Not sure where you're located, but a gravel driveway may help to soften the house versus asphalt or concrete. Soften up the area with grasses. Here's a link to a photo of grasses with a hot color palette http://www.spacemakerpress.com/catalogue/catimages/st05imgb.jpg You can always choose a more muted color palette as well. I would definitely tier the plan heights so they're taller against the house and gradually get lower. It would help to bring the house to human scale and not appear towering above. The pathway could be in a natural stone - the same color as the gravel driveway (if you can do gravel).

You have done a beautiful job of tucking plants into the crevices of your retaining walls. Your house trim color is perfect -- just slightly lighter in hue than the retaining wall blocks. First I would paint the big, flat gray wall slightly lighter than the blocks and slightly darker than the house trim. The concrete walk and stairs I would stain a mottled blend of the blocks and the house trim colors. Next would be to paint the railing black or the house body color. Now, think of the following as creating a light, airy trellise structure from the walk-level face of the (currently gray) wall to about 7' above the top of the wall (using 6x6" posts attached to the wall) with a corresponding line of posts sunk into the terrace level 2' in from the outside edge of the wall-attached posts. The inside posts would be about 6-8" higher than the outside posts. Put 4x4" wood to attach the outside line of posts to each other and do the same with the inside line of posts. Run wood pieces at the top of the two lines of posts from the inside line to the outside line at about a 45 degree angle. They would be cantilevered up at the terrace level. Across the top of the angled pieces create your top trellise boards which run parallel to the two lines of posts. OK. There you have your basic structure. You might want to extend the structure around to follow the street side of the terrace. You could then follow the suggestion of reom10 above about creating a bench-planter on the terrace side. Your spacing of the boards parallel to the gray wall and attached to the outside posts would determine how private you wanted your terrace to be. You might want to soften the terrace "floor" by using something irregular like flagstone with groundcover plantings between the stones. From the latticework on top of your structure you could hang seasonal flower baskets. Plant vines to go up the trellis and spill down the wall. How about planting a row of tall, narrow shrubs along the neighbor's fence above your terrace to help add to your privacy and make your yard feel less 'structured'? Or, how about patio table/s with umbrellas to block your neighbor's view? Anyway, you have a fun project ahead of you.

Bronan, Love the black trim around the window and door. I also think you have a nice start with the urns. Would you consider painting those black? You can also add striped hostas in around the base of the little trees. It will make them more prominent and hostas work well in formal spaces. They will be happy to share urn space until the tree gets too big but then you get a bigger urn anyway. I think the added greenery with the white stripes on the leaves will be beautiful with your house colors. Check with the garden nursery near you as some hostas are shade only and others can take some sun. They might suggest something even better... I don't know your budget but I would also suggest brick between the stone squares so guests don't have to leap frog to the porch :-) Good luck. I think you will have a nice space.

I agree with havingfun, thicken the supports and have something growing trailing up them. I didn't even notice there was a pergola until the close up. Right now it blends in too well with the house color, consider painting it a different color. I don't know your usda zone but classic climbers for a pergola include clematis, wisteria, grape https://www.houzz.com/photos/santa-ynez-valley-mediterranean-porch-santa-barbara-phvw-vp~2485412 or go for a modern look You can also hang string lights, planters or something from the beams. Also agree lighten the front door.